Internal combustion engines of all types are presently made primarily from metal components, many of which are in sliding metal-to-metal contact with each other. These include pistons contacting cylinder bores, camshaft lobes contacting lifters, rocker arms contacting valve stems, and distributor gears contacting camshafts.
To increase the efficiency of such engines it is important to reduce friction losses occurring at such sliding contact points so that the fuel energy is directed to producing output horsepower rather than in overcoming friction. To reduce friction, lubrication is usually used. Many such engines contain separate lubrication systems for ensuring the proper delivery of lubricants to the components having sliding metal contact. Such lubrication systems typically include a reservoir having a sump, an oil pump and a conduit system for delivering and returning the lubricating fluid to the moving parts of the engine.
Notwithstanding such lubrication, over time the components tend to wear. Much of this wear occurs during engine startup when the oil pressure is low. The engine components are not properly lubricated and engine wear occurs. Such wear creates fine metal particles which are washed down into the reservoir as the lubricant circulates through the system. As the particle-laden lubricant is drawn through the oil pump, the particles cause damage to the pump gears and cause even further wear. The lubricant is then normally delivered to a filter to be cleaned. However, when the lubricant temperature is low and the viscosity high, or when the engine is operating above an idle condition, a portion of the lubricant will bypass the filter. This unfiltered particle-laden lubricant will cycle directly through the crankshaft main journals, the connecting rod journals, the camshaft and lifters, the pushrods and rocker assemblies, and then back to the reservoir. The unfiltered lubricant impregnates the surface of the aluminum bearings with metal particles to cause the journals to wear. As a result, the life expectancy of the rotating assemblies and camshafts is greatly reduced.
To try to overcome this cycle of damage, various forms of magnetic collectors have been proposed in the past for use in separating metal particles from the lubricant as it passes through the reservoir.
Examples of prior magnetic collectors are provided in U.S. Pat. No. 1,806,001 (Simms et al), U.S. Pat. No. 2,032,800 (Haltenberger), U.S. Pat. No. 2,358,612 (Acker), U.S. Pat. No. 2,345,029 (Brooks) and U.S. Pat. No. 2,877,899 (Hutchins et al). These collectors commonly feature rigid magnets, such as bar magnets and horseshoe magnets, that are at least partially submerged within the lubricant. This submergence typically takes place in the reservoir, but at some distance from where the lubricant collects immediately prior to being taken up and pumped through the oil pump. A common failing of these prior magnetic collectors is that they show a magnetic field which is very limited, in the sense that it is only in effect over a small portion of the lubricant reservoir. Particles suspended in the fluid which pass outside of these limited magnetic fields of the prior art are simply not extracted. Locating the limited magnetic field a distance from the lubricant sump and intake leading to the pump also limits the prior designs' effectiveness.
An example of a magnetic collector having a slightly expanded magnetic field is provided by U.S. Pat. No. 2,755,932 (Cohn). The Cohn patent provides two or more bar magnets that are pivotally connected to the stem of a reservoir drain plug. When the plug is inserted into the reservoir the ends of the bar magnets repel each other causing the free ends of the bar magnets to pivot away from each other. While this arrangement is an improvement over the earlier described magnetic collectors, it still produces only a very limited magnetic field which is centralized about the reservoir drain plug. As before, the plug is typically located a distance from the oil uptake of the oil pump, so that much of the lubricating fluid can pass by the bar magnets without coming into close enough contact with the magnetic field created by the bar magnets for the metallic particles to be captured. Further, the ends of the magnet tend to be attracted to the oil pan itself, and this effect distorts the magnetic field further reducing the effectiveness of this prior device in removing particles. Thus, while perhaps slowing down somewhat the rate of wear damage caused by the metal particles, such wear damage is not effectively controlled by this prior design.
Using the drain plug as a place to introduce a magnetic extractor is problematic. The drain plug is typically located at the lowest point in the reservoir, at a position where the reservoir is quite wide. The introduction of a point source magnet into the lubrication system at a point where the flow is wide means that a substantial portion of the flow can pass by without being purified of metal debris, making the particle collection ineffective. What is needed is a collector that permits a magnetic field to be located at a predetermined position within a lubricant reservoir in such a manner that the magnetic field extends broadly to effectively comb the lubricant before it enters the oil pump intake. Such a collector could collect a substantial portion of the particles to prevent unnecessary damage to the internal machine elements and to effectively control the wear damage caused by such free metal particles. Such a collector should also be easily removable for inspection to allow a determination of how much metal debris is being collected to indicate how much wear there is. Thus, the collector can be used as a diagnostic tool to evaluate when to perform realignment of the components before the wear reaches such an extent that excessive permanent damage occurs.